1. Field of the Invention
The present invention is directed to a method of cleaning semiconductor devices and, more particularly, to a method of cleaning damaged layers and polymer residue on semiconductor devices.
2. Description of the Related Art
As the design rule of semiconductor device gets smaller, the contact region between layers decreases. Due to the small sizes involved, it is difficult to use conventional methods to form a contact region. Accordingly, a manufacturing process that self-aligns the contact pad with a semiconductor layer or an interconnect layer underlying the contact pad is employed for sub-quarter micron semiconductor devices. The resulting self-aligned contact (SAC) has the advantages of allowing increased margin for misalignment error during photolithography, and reducing contact resistance. In the case of forming the SAC, an etch technique having high selectivity is necessary.
However, it is difficult to remove the damage layer and polymer residue resulting from high-selectivity etch. Accordingly, a cleaning technique is required to remove the damage layer and polymer residue. A conventional cleaning solution contains APM (NH4OH/H2O2/H2O) or SPM (H2SO4/H2O2 mixture).
Metal layers are often used in order to increase the speed of semiconductor devices. However, conventional cleaning solutions such, as the foregoing solution, damage metal layers. Therefore, cleaning solutions with EKC (NH4OH/C6H4(OH)2/Aminoethoxyethanol) or SMF (NH4OH/CH3COOH/H2O/HF) are used. However, EKC and SMF solutions do not remove the damage layer and polymer residue resulting from etch processes; therefore, contact resistance increases and failures of semiconductor devices occur. Accordingly, there is a need for a method for removing the damaged layer and polymer residue without damaging the metal layer of a semiconductor device.
In accordance with one aspect of the present invention, there is provided a method of cleaning a semiconductor device which includes the steps of: mixing HF and ozone water in a vessel to form a solution of HF and ozone water; and dipping a semiconductor device in the vessel containing the solution of HF and ozone water, wherein the solution contains about 0.034 to about 0.077 wt % HF.
In a more specific embodiment, the ozone water contains about 5 to about 150 ppm ozone. In another more specific embodiment, the semiconductor device is dipped for about 1 to about 30 minutes.
Preferably, damaged layers and polymer residue are removed from the semiconductor device by the inventive method.
In accordance with another aspect of the present invention, there is provided a method of cleaning a semiconductor device including the steps of: mixing HF and ozone water in a vessel to form a solution of HF and ozone water; dipping a semiconductor device in the vessel containing the solution of HF and ozone water, and thereafter introducing ozone water into the vessel to replace the solution of HF and ozone water in the vessel, wherein the solution includes about 0.034 to about 0.077 wt % HF.
In more specific embodiments, ozone water is flowed into the vessel thereby causing an overflow of the solution of HF and ozone water out of the vessel. According to specific embodiments, the ozone water is flowed into the vessel thereby causing the overflow of the solution of HF and ozone water out of the vessel for a period between about 1 and about 30 minutes.
In accordance with a further aspect of the present invention, there is provided a method of cleaning a semiconductor device including the steps of: introducing HF and ozone water into a vessel to form a solution of HF and ozone water; mixing the HF and ozone water in the vessel to form a uniform solution of HF and ozone water; and dipping a semiconductor device in the vessel containing the uniform solution of HF and ozone water.
In more particular embodiments, the HF and ozone water are mixed to form a uniform solution by circulation, more specifically by means of a pump.
In specific embodiments, the HF and ozone water are circulated by flowing the HF and ozone water from an inner bath to an outer bath and pumped back into the inner bath.
In accordance with still another aspect of the present invention, there is provided a method of cleaning a semiconductor device including the steps of: introducing HF and ozone water into a vessel to form a solution of HF and ozone water; mixing the HF and ozone water in the vessel to form a uniform solution of HF and ozone water; dipping a semiconductor device in the vessel containing the uniform solution of HF and ozone water; and introducing ozone water into the vessel to replace the solution of HF and ozone water in the vessel.
Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.